Both are portable players, $1799 against $730. This page puts them side by side on the only three things a maker can be held to — power, output impedance and noise — and then asks the question that actually matters: which headphones do they treat differently?
The FiiO M17 reaches 100 dB on 567 of the 567 models here, the FiiO M33 R2R on 566.
| Specification | FiiO M17 | FiiO M33 R2R |
|---|---|---|
| Power into 32Ω | 500 mW | 470 mW |
| Power into 150Ω | 115 mW | 109 mW |
| Power into 300Ω | 63 mW | 60 mW |
| Power into 600Ω | 32 mW | 30 mW |
| Output impedance | 1 Ω | 0.8 Ω |
| Output noise | 3.5 µV | 5.5 µV |
| Price | $1799 | $730 |
| Headphones it reaches 100 dB on out of 567 | 567 | 566 |
A figure marked not published is missing from the maker’s own material, which is not the same as being good or bad. Where one of these two publishes a number and the other does not, the comparison on that axis cannot be made at all — and saying so is more useful than guessing.
1 headphone reaches 100 dB on the FiiO M17 but not on the FiiO M33 R2R — Symphonium Titan.
3 headphones are left alone by the FiiO M33 R2R under the one-eighth rule but coloured by the FiiO M17 (Shure AONIC 4, Simgot SuperMix 4, Symphonium Giant).
50 headphones stay below the audible-hiss threshold on the FiiO M17 but cross it on the FiiO M33 R2R (64 Audio Nio, 64 Audio U12t, 64 Audio U18s, 47 more).
566 of the 567 models here reach 100 dB on both. That is a power count and nothing more; whether either source suits a given headphone also depends on the two lines above.
Each has a page of its own with every power figure traced to what the maker published and a full headphone list: FiiO M17 and FiiO M33 R2R. Or put either against your own headphones in the source comparison tool.